Method of making liners for shaped charges



Jan. 28, 1964 H. D. OWEN ETAL 3,119,178

METHOD OF MAKING LINERS FOR SHAPED CHARGES Original Filed Sept. 17, 1959 INVENTOR.

United States Patent Office 3,ll9,l78 Patented. Jan. 28, 1954 2 Claims. (Cl. 294l7) Our invention relates to a method for making shaped charge liners, and more particularly to a method of making cone shaped liners for use with shaped charges of the type employed in perforating in bore holes.

This application is a division of our application Ser. No. 840,620, filed September 17, 1959.

Cone shaped charge liners of the type commonly used in the prior art of which we are aware, are subject to a number of disadvantages. For one thing, the conventional liners are formed in a number of drawing stages from a circular blank. In some cases, as many as five or six drawing stages are required in order to form a finished cone. Such forming procedure is tedious and time-con suming and requires substantial tooling, and consequently is relatively expensive. Furthermore, the drawing process results in cones having non-uniform thickness, internal stresses, and non-uniform density, with the result that the liner does not perform its function in an optimum manner.

It is accordingly the general object of our invention to provide a shaped charge liner wherein the disadvantages above mentioned are obviated.

Another obiect of our invention is to provide a method for making a shaped charge liner which does not involve a drawing operation.

Another object of our invention is to provide a method for making a shaped charge liner having uniform thickness and density.

Another object of our invention is to provide a method for making a shaped charge liner wherein no internal stresses are introduced into the liner.

Another object of our invention is to provide an economical method for making conical shaped charge liners.

These and other objects are effected by our invention as will be apparent from the following description taken in accordance with the accompanying drawings, forming a part of this application, in which:

FIG. 1 is a schematic perspective view of a charge liner in accordance with a preferred embodiment of our invention;

FIG. 2 is a schematic perspective view of a typical shaped charge of a type incorporating the liner of our invention;

FIG. 3 is a horizontal section view taken at the central axis of the shaped charge shown by FIG. 2; and

PEG. 4 is a schematic perspective view of a blank from which a liner in accordance with a preferred embodiment of our invention may be formed.

The shaped charges shown by FIGS. 2 and 3 are conventional in all respects except for the charge liner. These shaped charges include a hollow charge carrier body 11 open at one end and having a projecting portion 13 at the other end for receiving a charge support member 15. The charge is held in place on the support member by means of a set screw 17. The support member is a hollow tube which carries a length of detonating material known as primacord l). The charge carrier interior is shaped to define a cavity 21, generally cylindrical and having a concave rear end portion 23, the interior being adapted for receiving a conventional shaped explosive charge 25. The exterior surface of the shaped explosive charge is made to conform with the interior surface of the charge carrier body 11, as will be hereinafter more fully described. The shaped explosive charge 25 is hollow on the side facing the charge carrier open side to define a generally conical or frusto-conical cavity having its central axis coaxial with that of the charge carrier body 11. The shaped explosive charge liner 27, which is the feature of our invention, is carried within the charge carrier body 11 with its outer surface 29 conforming with the surface of the explosive charge conical cavity, as will be hereinafter more fully explained. The charge carrier body 11 is closed by a conventional cap 31 which makes a pressed fit with a flange 33 on the open end of the carrier body 11 and compresses a gasket 35 to seal the charge against entry of fluid or moisture.

In accordance with a preferred embodiment of our invention the charge liner 27 is simply a blank of suitable sheet metal material of such shape that when formed it makes a cone having a smfll apex opening 37. The cone material is preferably dead annealed tough pitch electrolytic copper sheet, the thickness of which will vary with the charge size, as will be hereinafter more fully explained. Silver also makes good liner material and could be used, but it is quite expensive. Other suitable liner materials could also be used in the practice of our invention. In general, materials having high thermal and electrical conductivity characteristics are suitable.

In actual practice the cone stock material is in the form of a roll of strip or band material the width of which is substantially equal to the greatest dimension of the liner blank to be cut from it. This material is reeled off the roll and passed through a blanking die, which cuts a blank with each stroke of its operation. The preferred form of the liner blank 39 is a half circle with a small half circle notch 41 cut at the center of the half circle diameter, or straight side 47. The blank 3) is then formed, by a forming die (not shown) in a single stroke operation, into the shape of a cone having a small apex opening 37. When the cone is in the forming die, the blank straight edges 47 are abutting, but when the liner is removed from the die these edges spring slightly outward leaving a narrow slit 45 in the cone side. A typical liner 27 after forming and ready for assembly into a shaped charge is shown by FIG. 1 of the drawings.

Where the liner blank 3% is a half circle, the formed cone will of course have a 60 degree apex angle, which is the apex angle most widely used in the industry. it is of course apparent that a greater or smaller portion of a circle could be used as the liner blank depending upon what apex angle is desired for the finished cone.

in assembly of the liner 27, and charge body 11, first the desired quantity of explosive 25 in granular form including a small quantity of booster explosive at the region of the charge carrier body interior closed end (or adjacent the cone apex) is placed in the carrier body cavity, and the body 11 is positioned below a die (not shown) which has conical head over which a liner 2,7 is placed. The die head is then moved downward, pressing the cone into place and compressing the explosive 25 so that it is a solid mass filling all the space between the liner 2'7 and the body cavity 2 1. The tip of the die head is blunt and terminates substantially at the liner apex, so that the booster portion of the explosive receives little compression. The length of the curved periphery 4.3 of the liner blank 39 is made such that when the liner 27 is formed and assembled with the gap or slit 4-5 closed, the cone base portion 43 will make a 0.001 to 0.002 inch interference fit with the carrier body cavity interior. While in the drawings the cone base 43 is shown as having an edge taper, this is not necessary, and in actual practice the edge is just a right angle cut relative to the cone surface.

The explosive material may be of any suitable type, as for example, Dupont RDX (cyclotrimethylenetrinitramine). The quantity of explosive used will depend on the size of the charge and may vary all the way from about five grams for a small charge to about 200 grams for a large charge. The thickness of the liner material may vary from about 0.019 inch for small charges to about 0.062 inch for large charges.

The charge liner of our invention has a number of important advantages over conventional liners. The con ventional liner is formed from a circular blank and requires five or six separate progressive drawing operations plus an annealing operation and a trimming operation. The liner of our invention requires only two operations, namely blanking and forming. No trimming is required. This means that our liners can be produced much more economically than conventional liners. In addition, liners in accordance with our invention are free of the hard spots, internal stresses, and thickness irregularities encountered in conventional liners as a result of the drawing process. This means that there is nothing in our liner to make the jet form at varying speeds, with the result that our liner is actually more effective. The size of the anex opening is not critical, but is made large enough to free the liner cone apex from excess metal when formed. While the liner with an apex opening is preferable, it should be understood that in some forms our invention may be practiced without the apex opening, or in other words, with no notch at the center of the blank radial sides. The apex opening, among other things, has the advantage that the booster char e is not compressed, which means that the explosive is more effective, so that the charge carrier for a given slot effect can be made smaller, or shorter in length. It should of course be understood that the specific charge carrier shown in the drawings is by way of example only and the liner of our l invention may be used in any type of charge carrier body in which a conventional type liner could be used.

While we have shown our invention in only one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications Without departing from the spirit thereof.

We claim:

1. The method of making a shaped charge liner which comprises the steps of:

(a) reeling liner stock material from a roll;

(5) passing said material through a blanking die;

(0) cutting a blank with each stroke of the operation of said blanking die to provide a circle sector blank with a small notch at the radial center thereof; and,

(d) forming each said blank in a single stroke of a forming die into the shape of a cone having a small apex opening while leaving the blank surface area substantially unchanged.

2. The method of making a shaped charge liner which comprises the steps of:

(a) reeling liner stock material from a roll;

(b) passing said material through a blanking die;

(c) cutting a blank with each stroke of the operation of said blanking die to provide a circle sector blank; and,

(d) forming each said blank in a single stroke of a forming die into the shape of a cone having a small apex opening while leaving the blank surface area substantially unchanged.

Brierly et al. Feb. 24, 1942 West Sept. 23, 1947 

1. THE METHOD OF MAKING A SHAPED CHARGE LINER WHICH COMPRISES THE STEPS OF: (A) REELING LINER STOCK MATERIAL FROM A ROLL; (B) PASSING SAID MATERIAL THROUGH A BLANKING DIE; (C) CUTTING A BLANK WITH EACH STROKE OF THE OPERATION OF SAID BLANKING DIE TO PROVIDE A CIRCLE SECTOR BLANK WITH A SMALL NOTCH AT THE RADIAL CENTER THEREOF; AND, (D) FORMING EACH SAID BLANK IN A SINGLE STROKE OF A FORMING DIE INTO THE SHAPE OF A CONE HAVING A SMALL APEX OPENING WHILE LEAVING THE BLANK SURFACE AREA SUBSTANTIALLY UNCHANGED. 